A SIP-based network architecture is defined allowing a variety of access methods for interfacing QSIG-based signaling devices. The QSIG-based signaling devices are typically enterprise-based PBXs that either interface directly via QSIG, or adapt QSIG signaling to related signaling protocols via gateways, which can be customer premise or network based. The gateways can either interwork QSIG signaling or tunnel QSIG signaling over H.323, SIP, or other protocols. Upon reaching the SIP-based network, Session Border Controllers process the signaling. The Session Border Controllers terminate the tunnel (if used) and extracts the QSIG signaling for interworking to SIP, thereby facilitating a homogeneous SIP- based core network. In addition to interworking QSIG signaling, the Session Border Controllers perform other signaling related functions for the SIP-based network that are performed at a point as near as possible to the network's edge.